Google just launched Google Sync, a service that will allow you to synchronize contacts and calendar from gmail to a mobile phone. A wide variety of devices are supported including Windows Mobile, Symbian, Blackberry.
For more information check out http://www.google.com/mobile/default/sync.html.
Synchronize your contacts. Get your Google contacts
quickly and easily to your phone. With Sync, you can have access to
your address book at anytime and place that you need it.
Get calendar alerts. Using your
phone’s native calendar, you can now access your Google calendar, and
be alerted for upcoming appointments with sound or vibration.
Always in sync. Your contacts stay
synchronized whether you access them from your phone or from your
computer. Add or edit contact information right on your device or on
your Google account on the web.